This invention relates to aromatic diamines containing uret dione and urea groups corresponding to a specified formula and to a process for the production of such diamines.
Uret dione diamines, i.e. aromatic diamines containing uret dione groups in the same molecule and corresponding to the general formula ##STR2## are known to those skilled in the art. Such diamines are useful in incorporating uret dione groups into polyurethanes hardenable by heat (German Offenlegungsschrift No. 2,044,838). They may also be employed in the production of wash-resistant dye finishes on cellulose fibers (U.S. Pat. No. 2,643,250). In such dye finishes, the uret dione diamine is first attached to the cellulose fiber through the uret dione group and the amino groups are then diazotized. The production of aromatic uret dione diamines by the nitration of uret diones, followed by hydrogenation disclosed in U.S. Pat. No. 2,643,250 is, however, extremely complicated.
Aliphatic uret dione diamines are largely unstable. Thus, dimeric tolylene diisocyanate reacts with aliphatic amines even at temperatures below 50.degree. C. and the uret dione ring splits to form urea and biuret groups (JACS 75 (1953) page 5439 and Can. J. Chem. 40 (1962), page 935). This feature of the uret dione group is utilized in the crosslinking of polyurethanes containing uret dione groups by the action of aliphatic diamines (for example, ethylene diamine) to produce crosslinked polyurethane filaments and fibers (German Offenlegungsschrift No. 2,044,838). The less reactive aromatic amines are also capable of splitting the uret dione ring in polyurethanes in solution in dimethyl formamide or dimethyl sulfoxide.
In accordance with German Offenlegungsschriften Nos. 2,941,051, 2,842,805 and 1,570,548, aromatic diamines may be used as chain extenders in addition to dimeric tolylene diisocyanate to produce one-component polyurethane mixtures. However, specific adducts of dimeric tolylene diisocyanate with excesses of diamines are not described in these disclosures.